Physicist Pekka Janhunen with the Finnish Meteorological Institute has developed a novel idea to colonize a place other than the Earth—and it is not the moon or Mars. Instead, Janhunen is suggesting in a paper posted on the arXiv preprint server that humans populate a giant satellite that orbits Ceres, a dwarf planet in the asteroid belt between Jupiter and Mars.

Many space scientists have noted the difficulties and dangers of attempting to colonize either the moon or Mars—both have extremely hostile environments. So many in the field have been promoting the idea of building a structure large enough to host tens of thousands of people somewhere in space. But doing so would present its own set of problems. Paying for the construction of such a mammoth project, for example, and protecting the inhabitants from solar radiation—and what about providing gravity, and where would the structure reside? In his paper, Janhunen suggests that Ceres would be an ideal place to put such a structure, which would make it a satellite. He notes that such an orbit would be close enough to the dwarf planet that a 636-mile-long space elevator could carry material from the surface to the satellite for construction and resupply—Ceres has more than enough nitrogen, water and carbon dioxide to support such a venture.

Two scientists from CNRS and Sorbonne University working at the Institute of Celestial Mechanics and Ephemeris Calculation (Paris Observatory—PSL/CNRS) have just shown that the influence of Saturn's satellites can explain the tilt of the rotation axis of the gas giant. Their work, published on 18 January 2021 in the journal Nature Astronomy, also predicts that the tilt will increase even further over the next few billion years.

Rather like David versus Goliath, it appears that Saturn's tilt may in fact be caused by its moons. This is the conclusion of recent work carried out by scientists from the CNRS, Sorbonne University and the University of Pisa, which shows that the current tilt of Saturn's rotation axis is caused by the migration of its satellites, and especially by that of its largest moon, Titan.

Recent observations have shown that Titan and the other moons are gradually moving away from Saturn much faster than astronomers had previously estimated.